用C# 编写一个控制台应用程序,从键盘上输入3个数,输出这3个数的平均数.

你试试 这个
public class AverageNum
{
public static void Main(String[] args)
{
int num1;
int num2;
int num3;
int sum;
int avernum;
Console.Write(" Enter First integer: ");
num1 = Convert.ToInt32(Console.ReadLine());
Console.Write(" Enter Second integer: ");
num2 = Convert.ToInt32(Console.ReadLine());
Console.Write(" Enter Three integer: ");
num3 = Convert.ToInt32(Console.ReadLine());
sum = num1 + num2 + num3;
avernum = sum / 3;
Console.WriteLine("Average is {0}", avernum);
}
}